/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.dolphinscheduler.plugin.task.sql;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.google.common.base.Strings;

public class SqlSplitter {

  private SqlSplitter() {
  }

  private static final String LINE_SEPARATOR = "\n";

  /**
   * split sql by segment separator
   * <p>The segment separator is used
   * when the data source does not support multi-segment SQL execution,
   * and the client needs to split the SQL and execute it multiple times.</p>
   *
   * @param sql
   * @param segmentSeparator
   * @return
   */
  public static List<String> split(String sql, String segmentSeparator) {
    if (Strings.isNullOrEmpty(segmentSeparator)) {
      return Collections.singletonList(sql);
    }

    String[] lines = sql.split(LINE_SEPARATOR);
    List<String> segments = new ArrayList<>();
    StringBuilder stmt = new StringBuilder();
    for (String line : lines) {
      if (line.trim().isEmpty() || line.startsWith("--")) {
        continue;
      }
      stmt.append(LINE_SEPARATOR).append(line);
      if (line.trim().endsWith(segmentSeparator)) {
        segments.add(stmt.toString());
        stmt.setLength(0);
      }
    }
    if (stmt.length() > 0) {
      segments.add(stmt.toString());
    }
    return segments;
  }
}
